UFO2000 is free and opensource turn based tactical squad simulation game with multiplayer support.

While having its own engine written from scratch, the game still relies on the data files from the famous X-COM: UFO Defense. That's why it looks very much like a multiplayer mod for X-COM.

UFO2000 project is written in portable C and is known to compile and run on Linux, FreeBSD.

You need data files from the original X-COM to play UFO2000 (we are working on making our own free set of graphics, if you want to help us, check this link). The game can also work with data files from X-COM demo, but you will be only able to play on 'City' map and use a limited set of units in this case.